Iron deficiency in women: symptoms, tests and treatment

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Iron deficiency is easy to overlook because it builds slowly and its main symptom, tiredness, has so many possible causes. Yet it is one of the most common and most treatable problems in women. Knowing the signs, the right test to ask for, and how to treat it safely means you can catch it early rather than living with it for months.

Why women are at higher risk

How common iron deficiency is depends on where you draw the line. In a study of women of reproductive age, 18.9% were deficient using a ferritin cut-off of 15, but 45.8% were using a cut-off of 30 (Eur J Clin Nutr, 2025). The reason is simple: periods cause a monthly loss of iron, and diet does not always keep up. Several things raise the risk further:

Heavy periods, the most common driver in women who still menstruate
Pregnancy, when iron needs rise sharply
A plant-based diet, since plant iron is absorbed less well
Gut conditions like celiac disease that reduce absorption
Regular endurance exercise and frequent blood donation

Chart of ferritin results in women of reproductive age. 18.9% fall below 15 ng/mL and count as deficient under either standard. A further 26.9% fall between 15 and 30, so they count as deficient only under the stricter cut-off, making 45.8% in total. The remaining 54.2% are at 30 ng/mL or above. — Two accepted cut-offs, one group of women. Which number you are told depends on which line your lab draws.

Deficiency comes before anemia

A common misunderstanding is that a normal blood count rules iron deficiency out. It does not. Iron deficiency develops in stages: first your stored iron runs down, then, only later, your hemoglobin falls into the anemia range. Anemia is a late manifestation of iron deficiency, not the start of it (Clinical Medicine, 2021). Symptoms like fatigue, hair shedding and restless legs can appear during that first stage, while a standard blood count still looks normal. That is why the stores test, ferritin, matters so much: it catches the problem before anemia sets in.

Symptoms to watch for

Low iron often shows up before full anemia. Common signs include:

Fatigue and low energy, usually the first clue
Breathlessness and palpitations
Hair shedding and brittle nails
Restless legs that disturb sleep, headaches and poor concentration
Cold hands and feet, a sore tongue, or an unusual craving to chew ice
Lightheadedness, which has several causes worth telling apart before you assume it is iron

Some women have no symptoms at all and are found on a routine blood test.

Grid showing what ferritin, a full blood count and symptoms each show across three stages: stores running down, stores empty, and anemia. The blood count reads normal through the first two stages while symptoms can already be present. — The blood count is normal through the stages where symptoms start. Ferritin is the test that sees them.

The tests that find it

The main test is ferritin, which reflects your iron stores, alongside a complete blood count. In a woman without evidence of inflammation, ferritin below about 30 ng/mL strongly supports iron deficiency, and a level below 15 is clearly low. Because ferritin also rises with inflammation, your doctor may add a full iron panel, or an inflammation marker, if the result is borderline or does not fit your symptoms.

Iron-rich foods and how to absorb them

Food is the foundation, and how you combine it changes how much iron you actually take in. For the full list of sources and absorption tactics, see our guide to iron-rich foods.

Type	Foods	Absorption
Heme iron (animal)	Red meat, liver, fish, shellfish	Absorbed well
Non-heme iron (plant)	Beans, lentils, tofu, spinach, fortified cereals	Absorbed less well; needs help

Two simple habits make a real difference:

Add vitamin C to plant-iron meals, from citrus, peppers, tomatoes or a squeeze of lemon, which boosts absorption.
Keep tea and coffee away from iron meals, since the tannins block absorption, as does a large amount of calcium at the same time.

Our iron intake calculator shows how much iron your life stage needs.

Taking a supplement well

If your doctor advises a supplement, the formulation, dose and schedule should reflect the deficiency, your response and any side effects. All oral forms can upset digestion. Our iron guide explains how clinicians use daily or every-other-day schedules, and iron supplement forms compared explains the elemental iron each preparation delivers without presenting one form as best for everyone.

Heme iron from animal foods against non-heme iron from plants, with what to eat alongside a plant-iron meal, vitamin C, and what to keep away from it, tea, coffee and a large amount of calcium. — Plant iron is the one that depends on what sits next to it on the plate.

Correct it, then find the cause

A useful rule: correct a confirmed deficiency, then find and fix the cause, and recheck. Ferritin is retested after a few months to confirm your stores are rebuilding, which takes time. Taking iron long term without knowing why you are low can hide a problem that needs attention. That matters especially for postmenopausal women, in whom new iron deficiency is not explained by periods and should be investigated properly.

When to see a doctor

See your doctor if you have ongoing tiredness, breathlessness, heavy periods or hair shedding, and ask specifically about a ferritin test rather than a standard blood count alone. Iron deficiency is simple to test for and treat, and the cause matters as much as the number.

Frequently asked questions

How common is iron deficiency in women?

Very common. Around one in five women is iron deficient, mainly because monthly periods cause a steady loss of iron that diet does not always replace. It is one of the most frequent nutritional deficiencies worldwide.

What are the symptoms of iron deficiency?

Fatigue is usually first, often before anemia develops. Others include breathlessness, palpitations, brittle nails, hair shedding, restless legs, headaches, poor concentration and, sometimes, a craving to chew ice. Some women have no symptoms and are found on a blood test.

Can you be iron deficient without anemia?

Yes, and it is common. Your iron stores, measured by ferritin, can run low and cause symptoms like fatigue and hair shedding before your hemoglobin falls into the anemia range. This is why ferritin, not just a standard blood count, is the test that catches it early.

Which tests diagnose iron deficiency?

Ferritin, which reflects your iron stores, is the main test, alongside a complete blood count. In a woman without evidence of inflammation, ferritin below about 30 ng/mL strongly supports iron deficiency. Because ferritin rises with inflammation, your doctor may add a full iron panel if the result is borderline or does not fit the clinical picture.

How is iron deficiency treated?

By finding the cause, often heavy periods, increasing dietary iron with vitamin C to aid absorption, and taking an iron supplement if your doctor advises one. Levels are rechecked after a few months to confirm your stores are rebuilding.

References

Iron deficiency without anaemia: a diagnosis that matters · Al-Naseem A, Clinical Medicine (London), 2021;21(2):107-113
Iron status in women of reproductive age: the role of inflammation and ferritin thresholds · European Journal of Clinical Nutrition, 2025
Effectiveness of dietary interventions to treat iron-deficiency anaemia in women · PMC / NIH
Tiredness and fatigue · NHS